<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        .root {
            display: flex;
        }

        .root div {
            height: 100px;
        }

        .left,
        .right {
            width: 300px;
            background-color: aqua;
        }

        .center {
            flex: 1;
            background-color: blueviolet;
        }
    </style>
</head>

<body>
    <div class="root">
        <div class="left">left</div>
        <div class="center">center Lorem ipsum dolor sit, amet consectetur adipisicing elit. Ipsa ea commodi neque
            exercitationem optio tempora velit facere maxime dignissimos molestias numquam, ut similique eius a sint
            quis, vitae, ex perferendis.</div>
        <div class="right">right</div>
    </div>
</body>

</html>